1. Field of the Invention
The present invention relates to a preparation process of a polymer by the ring-opening polymerization of a 4- to 10-membered cyclic monomer. Such polymer is important for use in preparation of resin materials and fibers.
2. Related Art of the Invention
An anionic polymerization or a nucleophilic polymerization has been well known as one of the process for conducting ring-opening polymerization of a ring-opening polymerizable cyclic monomer. The polymerization initiators which can be generally used are alkali or alkaline earth metals, compounds thereof, other metallic compounds and amines [T. Saegusa, Ring-opening Polymerization (1), Published from Kagaku Dojin (1971), chapter 2.3.3; Polymer Functional Material Series (2), Synthesis and Reaction of Polymer (2), Edited by Polymer Society of Japan, Published from Kyoritsu Shuppan Co. (1991), chapter 1.2].
However, in some cases, physical properties and thermal stability of the polymer obtained by using the initiators which contain these metals are remarkably damaged by residual metallic ingredients. Consequently, the preparation process of these polymers requires a specific method or a complex step for sufficiently removing these metallic ingredients. On the other hand, amine initiators, which are of non-metal, have still problems on insufficient polymerization activity and residual amine odor.
Further, polymerization of a lactam or a cyclic siloxane performed in the presence of a non-metallic phosphazene compound has been known [U.S. Pat. No. 5,399,662; Macromol. Rapid Commun., 16, 449-453 (1995); Macromol. Symp., 107, 331-340 (1996)]. The phosphazene compound has a strongly basic property and can be an effective initiator in these processes. However, a complex process is required for preparing the phosphazene compound. Furthermore, on the preparation of the phosphazene compound, more strongly basic compound such as sodium amide must be used in order to provide strongly basic property to the phosphazene compound. Those matters are quite unfavorable in industry. Moreover, on handling the phosphazene compound, the deterioration by carbon dioxide in the air often arises due to strongly basic property of the phosphazene compound.